Multi-channel electromyography during maximal isometric and dynamic contractions

Motor unit behavior differs between contraction types at submaximal contraction levels, however is challenging to study during maximal voluntary contractions (MVCs). With multi-channel surface electromyography (sEMG), mean physiological characteristics of the active motor units can be extracted. Two 8-electrode sEMG arrays were attached on biceps brachii muscle (one on each head) to examine behavior of sEMG variables during isometric, eccentric and concentric MVCs of elbow flexors in 36 volunteers.On average, isometric (364 ± 88 N) and eccentric (353 ± 74 N) MVCs were higher than concentric (290 ± 73 N) MVC (p < 0.001). Mean muscle fiber conduction velocity (CV) was highest during eccentric MVC (4.42 ± 0.49 m/s) than concentric (4.25 ± 0.49 m/s, p < 0.01) and isometric (4.14 ± 0.45 m/s, p < 0.001) MVCs. Furthermore, eccentric MVC showed lower sEMG amplitude at the largest elbow joint angles (120–170°) and higher CV at the smallest (70–150°) elbow joint angles (p < 0.05–0.001) than concentric MVC.The differences in CV and sEMG amplitude between the MVCs suggest that the control strategy of motor units differs between the contraction types during MVCs, and is dependent on the muscle length between the dynamic MVCs.     

The association between the total antioxidant potential of plasma and the presence of coronary heart disease and renal dysfunction in patients with NIDDM

Oxidative stress may be an important pathogenetic factor in the development of diabetic vascular complications. The total antioxidative potential of plasma reflects the ability of an individual to resist oxidative stress. We measured the plasma total peroxyl radical-trapping potential (TRAP) and the concentrations of four plasma chain-breaking antioxidants in 81 patients with non-insulin-dependent diabetes mellitus (NIDDM) nine years after diagnosis and in 102 well-matched non-diabetic control subjects. The association between the total antioxidative potential and the presence of coronary heart disease (CHD) and diabetic kidney disease were also studied. There were no significant differences in plasma TRAP between NIDDM patients and control subjects (1250 ± 199 vs. 1224 ± 198 μM). Nor were there any significant differences in the concentrations of plasma uric acid, ascorbic acid, α-tocopherol, and protein thiols between NIDDM patients and control subjects. Patients with a low glomerular filtration rate and/or high urinary albumin excretion had elevated plasma uric acid. Plasma TRAP was not, however, associated with renal dysfunction. The plasma of NIDDM patients with CHD had a significantly higher value of unidentified antioxidative potential than that of patients without CHD. This relation was strongly dependent upon smoking. In conclusion, these data demonstrate that there are no major defects in the antioxidative potential of plasma caused by NIDDM per se. CHD and diabetic renal dysfunction were not associated with changes in plasma TRAP.     

Background levels of hydrogen cyanide in human breath measured by infrared cavity ring down spectroscopy

Hydrogen cyanide (HCN) in breath has been suggested as a diagnostic tool for cyanide poisoning and for cyanide-producing bacterial infections. To distinguish elevated levels of breath HCN, baseline data are needed. Background levels of HCN were measured in mixed exhaled air from 40 healthy subjects (26 men, 14 women, age 21–61 years; detection limit: 1.5?ppb; median: 4.4?ppb; range <1.5–14?ppb) by near-infrared cavity ring down spectroscopy (CRDS). No correlation was observed with smoking habits, recent meals or age. However, female subjects had slightly higher breath levels of HCN than male subjects. CRDS has not previously been used for this purpose.     

Serum proteomics in amnestic mild cognitive impairment

We have explored proteins related to mild cognitive impairment (MCI). The serum proteome of 35 amnestic MCI patients and 35 cognitively healthy persons was investigated by LC MS. We identified 108 differentially expressed peptides between MCI patients and controls, belonging to 39 proteins. Eight proteins were selected for further investigation by quantitative protein measurements using a MRM assay; apolipoprotein E, carboxypeptidase N subunit 2, complement factor B (CFAB), galectin‐3 binding protein (LG3BP), lumican, serum amyloid A‐4 protein (SAA4), serum amyloid P‐component, and sex hormone binding globulin. Results of the quantitative protein measurements showed significantly decreased levels of carboxypeptidase N subunit 2, CFAB, LG3BP, SAA4, and serum amyloid P‐component in serum from amnestic MCI patients compared with cognitive healthy controls (two‐sided t‐test; p < 0.05). Apolipoprotein E and lumican showed no significant difference in protein levels, sex hormone binding globulin could not be quantified since the MRM assay did not reach the required sensitivity. A model based on the three most significantly decreased proteins (CFAB, LG3BP, and SAA4) showed a sensitivity and specificity of 73 and 66%, respectively, for the initial sample set. A small external validation set yielded 77% sensitivity and 75% specificity.     

Multi‐generational long‐distance migration of insects: studying the painted lady butterfly in the Western Palaearctic

Long‐range, seasonal migration is a widespread phenomenon among insects, allowing them to track and exploit abundant but ephemeral resources over vast geographical areas. However, the basic patterns of how species shift across multiple locations and seasons are unknown in most cases, even though migrant species comprise an important component of the temperate‐zone biota. The painted lady butterfly Vanessa cardui is such an example; a cosmopolitan continuously‐brooded species which migrates each year between Africa and Europe, sometimes in enormous numbers. The migration of 2009 was one of the most impressive recorded, and thousands of observations were collected through citizen science programmes and systematic entomological surveys, such as high altitude insect‐monitoring radar and ground‐based butterfly monitoring schemes. Here we use V. cardui as a model species to better understand insect migration in the Western Palaearctic, and we capitalise on the complementary data sources available for this iconic butterfly. The migratory cycle in this species involves six generations, encompassing a latitudinal shift of thousands of kilometres (up to 60 degrees of latitude). The cycle comprises an annual poleward advance of the populations in spring followed by an equatorward return movement in autumn, with returning individuals potentially flying thousands of kilometres. We show that many long‐distance migrants take advantage of favourable winds, moving downwind at high elevation (from some tens of metres from the ground to altitudes over 1000 m), pointing at strong similarities in the flight strategies used by V. cardui and other migrant Lepidoptera. Our results reveal the highly successful strategy that has evolved in these insects, and provide a useful framework for a better understanding of long‐distance seasonal migration in the temperate regions worldwide.     

Mammalian Target of Rapamycin (mTor) Mediates Tau Protein Dyshomeostasis: IMPLICATION FOR ALZHEIMER DISEASE*

Previous evidence from post-mortem Alzheimer disease (AD) brains and drug (especially rapamycin)-oriented in vitro and in vivo models implicated an aberrant accumulation of the mammalian target of rapamycin (mTor) in tangle-bearing neurons in AD brains and its role in the formation of abnormally hyperphosphorylated tau. Compelling evidence indicated that the sequential molecular events such as the synthesis and phosphorylation of tau can be regulated through p70 S6 kinase, the well characterized immediate downstream target of mTor. In the present study, we further identified that the active form of mTor per se accumulates in tangle-bearing neurons, particularly those at early stages in AD brains. By using mass spectrometry and Western blotting, we identified three phosphoepitopes of tau directly phosphorylated by mTor. We have developed a variety of stable cell lines with genetic modification of mTor activity using SH-SY5Y neuroblastoma cells as background. In these cellular systems, we not only confirmed the tau phosphorylation sites found in vitro but also found that mTor mediates the synthesis and aggregation of tau, resulting in compromised microtubule stability. Changes of mTor activity cause fluctuation of the level of a battery of tau kinases such as protein kinase A, v-Akt murine thymoma viral oncogene homolog-1, glycogen synthase kinase 3β, cyclin-dependent kinase 5, and tau protein phosphatase 2A. These results implicate mTor in promoting an imbalance of tau homeostasis, a condition required for neurons to maintain physiological function.     

Mitochondrial DNA and Y-chromosomal diversity in ancient populations of domestic sheep (Ovis aries) in Finland: comparison with contemporary sheep breeds

Background

Several molecular and population genetic studies have focused on the native sheep breeds of Finland. In this work, we investigated their ancestral sheep populations from Iron Age, Medieval and Post-Medieval periods by sequencing a partial mitochondrial DNA D-loop and the 5’-promoter region of the SRY gene. We compared the maternal (mitochondrial DNA haplotypes) and paternal (SNP oY1) genetic diversity of ancient sheep in Finland with modern domestic sheep populations in Europe and Asia to study temporal changes in genetic variation and affinities between ancient and modern populations.

Results

A 523-bp mitochondrial DNA sequence was successfully amplified for 26 of 36 sheep ancient samples i.e. five, seven and 14 samples representative of Iron Age, Medieval and Post-Medieval sheep, respectively. Genetic diversity was analyzed within the cohorts. This ancient dataset was compared with present-day data consisting of 94 animals from 10 contemporary European breeds and with GenBank DNA sequence data to carry out a haplotype sharing analysis. Among the 18 ancient mitochondrial DNA haplotypes identified, 14 were present in the modern breeds. Ancient haplotypes were assigned to the highly divergent ovine haplogroups A and B, haplogroup B being the major lineage within the cohorts. Only two haplotypes were detected in the Iron Age samples, while the genetic diversity of the Medieval and Post-Medieval cohorts was higher. For three of the ancient DNA samples, Y-chromosome SRY gene sequences were amplified indicating that they originated from rams. The SRY gene of these three ancient ram samples contained SNP G-oY1, which is frequent in modern north-European sheep breeds.

Conclusions

Our study did not reveal any sign of major population replacement of native sheep in Finland since the Iron Age. Variations in the availability of archaeological remains may explain differences in genetic diversity estimates and patterns within the cohorts rather than demographic events that occurred in the past. Our ancient DNA results fit well with the genetic context of domestic sheep as determined by analyses of modern north-European sheep breeds.     

Phylogenetic beta diversity in bacterial assemblages across ecosystems: deterministic versus stochastic processes

Increasing evidence has emerged for non-random spatial distributions of microbes, but knowledge of the processes that cause variation in microbial assemblage among ecosystems is lacking. For instance, some studies showed that deterministic processes such as habitat specialization are important, while other studies hold that bacterial communities are assembled by stochastic forces. Here we examine the relative influence of deterministic and stochastic processes for bacterial communities from subsurface environments, stream biofilm, lake water, lake sediment and soil using pyrosequencing of the 16S ribosomal RNA gene. We show that there is a general pattern in phylogenetic signal in species ecological niches across recent evolutionary time for all studied habitats, enabling us to infer the influences of community assembly processes from patterns of phylogenetic turnover in community composition. The phylogenetic dissimilarities among-habitat types were significantly higher than within them, and the communities were clustered according to their original habitat types. For communities within-habitat types, the highest phylogenetic turnover rate through space was observed in subsurface environments, followed by stream biofilm on mountainsides, whereas the sediment assemblages across regional scales showed the lowest turnover rate. Quantifying phylogenetic turnover as the deviation from a null expectation suggested that measured environmental variables imposed strong selection on bacterial communities for nearly all sample groups. For three sample groups, spatial distance reflected unmeasured environmental variables that impose selection, as opposed to spatial isolation. Such characterization of spatial and environmental variables proved essential for proper interpretation of partial Mantel results based on observed beta diversity metrics. In summary, our results clearly indicate a dominant role of deterministic processes on bacterial assemblages and highlight that bacteria show strong habitat associations that have likely emerged through evolutionary adaptation.     

Spatial structure in ecological communities – a quantitative analysis

The spatial structure of communities has recently gained much attention in ecology. Spatial structure comprises an important element in communities, but the literature lacks a thorough investigation about possible among‐organism or among‐ecosystem differences in the degree of spatial structure. Here, I conducted a quantitative review to determine if the degree of spatial structure varied predictably between the major organism types and ecosystems. Spatial structure was quantified as the relative fraction of community variation explained purely by spatial variables (fraction S/E). I integrated data from 322 variation partition analyses both in a generalized linear model (GLM) and using a boosted regression tree method, and showed that a mean of 11.0% of the variation in community composition was explained purely by spatial variables. Across all taxa, a body size–S/E relationship was positive. In GLM, fraction S/E increased highly significantly with study extent, it was highest among terrestrial taxa and higher in ectotherms than in homoiotherms. Spatial structure was also higher in omnivores than in autotrophs. These results suggest that the degree of spatial structure is jointly driven by extrinsic factors such as study extent and ecosystem type, and intrinsic factors such as body size, thermoregulation and interactions between body size and dispersal mode. These results should be important not only for basic research, but also conservation and bioassessment programs would benefit from the information about the magnitude of spatial variation in nature. Synthesis Spatial processes comprise an important element in most ecological communities, but the degree to which spatial structure varies across organisms or ecosystems is poorly known. Here, a quantitative review of 322 variation partition analyses indicated that spatial component varied predictably across ecological communities – it was driven by study extent and ecosystem type as well as by species traits such as body size and thermoregulation. These results give deep insights into the magnitude of spatial variation in nature and should be highly beneficial for conservation and bioassessment programs that are built on the information about how communities vary in space.     

Voluntary exercise normalizes the proteomic landscape in muscle and brain and improves the phenotype of progeroid mice

The accumulation of mitochondrial DNA (mtDNA) mutations is a suspected driver of aging and age‐related diseases, but forestalling these changes has been a major challenge. One of the best‐studied models is the prematurely aging mtDNA mutator mouse, which carries a homozygous knock‐in of a proofreading deficient version of the catalytic subunit of mtDNA polymerase‐γ (PolgA). We investigated how voluntary exercise affects the progression of aging phenotypes in this mouse, focusing on mitochondrial and protein homeostasis in both brain and peripheral tissues. Voluntary exercise significantly ameliorated several aspects of the premature aging phenotype, including decreased locomotor activity, alopecia, and kyphosis, but did not have major effects on the decreased lifespan of mtDNA mutator mice. Exercise also decreased the mtDNA mutation load. In‐depth tissue proteomics revealed that exercise normalized the levels of about half the proteins, with the majority involved in mitochondrial function and nuclear–mitochondrial crosstalk. There was also a specific increase in the nuclear‐encoded proteins needed for the tricarboxylic acid cycle and complex II, but not in mitochondrial‐encoded oxidative phosphorylation proteins, as well as normalization of enzymes involved in coenzyme Q biosynthesis. Furthermore, we found tissue‐specific alterations, with brain coping better as compared to muscle and with motor cortex being better protected than striatum, in response to mitochondrial dysfunction. We conclude that voluntary exercise counteracts aging in mtDNA mutator mice by counteracting protein dysregulation in muscle and brain, decreasing the mtDNA mutation burden in muscle, and delaying overt aging phenotypes.